Custom computer for music production - need help with parts

I'm going to build a desktop in a few months mainly for music production. I've built many computers before, however never one for just audio. Budget is around $700, so how should I delegate this budget to each of the components? For example, I know a good chunk of it should go to a large storage drive and lots of memory (about 16gb?), but how important is the processor? Should I spend the extra $100 to get hyperthreading from a i7 3770k or would a i5 3570k be sufficient? I'm not sure if music production uses a lot of transcoding that would benefit from as many CPU cores as possible.

I don't need a monitor, mouse/keyboard, or OS.

CPU is important, but i would focus more money into ram and hard drives first. then, silencing your system, and the audio interface if that is to be included in the $700.

What OS are you using?

If this is a custom build - it's almost certainly going to be windows.

I'm a radio engineer myself - which means that I build PC's that do audio playout/recording/encoding 24/7 in mission critical environments.

Production has its own can of worms that gets opened, but a lot of this stuff is common across workflows (we also do production at my facility, although much of that is done in the analog world).

First, we're going to need to get some background on what exactly you are doing. Are you working in Fruity Loops or something like that, or are you doing a more traditional multitrack mixdown?

The biggest thing that will suck up your CPU are any kind of effects plugins - reverb, compression, et cetera. If you're using VST instruments, those are going to eat up CPU and RAM as well.

Another huge question will be whether you are going to need to record outside sources, and if so, how many? Obviously you will need some type of soundcard for monitoring, but I/O capacity is a huge decision maker when it comes to hardware selection. My favorite company for soundcards is Echo Audio - I have several of their PCI cards which have been on air 24/7 for over a year and they are absolutely rock solid. Keep in mind that many audio interfaces are still using standard PCI.

If you're looking to save some money, I would grab some studio monitors with S/PDIF inputs, then get a motherboard that uses an Intel audio codec (no realtec or other crap!), then send the audio out over S/PDIF. Note that this will only help you if you do not need to record anything from the outside world, or you can get away with only a single mic (Alesis and Shure make XLR to USB, which are mic preamps with phantom power with a built in ADC).

In terms of hard drives: I absolutely insist on RAID 1 - no, it's not a backup - but it's the kind of thing that can really save your ass in an emergency. I've had machines lose a recording session due to piss-poor storage design (this was a Mac Pro that I didn't have a say in configuring).

I'd advise sticking with a system that's expandible. RAM is pretty cheap now ($40 for 8GB DDR3) so you can afford to splurge on that. I like Intel server boards (have a couple Z68's on air) - the main thing is that you do not want any cheap flaky hardware in your system (I go Intel for everything - Intel NIC, Intel HBA, et cetera). These are the kinds of things that will bite you in the behind - crap drivers running in kernel space are going to kill your performance and your reliability.

The machines I build for radio use are based around an Intel server motherboard, an i3-2100, 8GB RAM. Runs about $500 without case. Depending on how many projects you want to have going at one time, I'd grab a pair of 1TB drives (RAID 1). If you want to do really serious multitrack recording, you want to use different drive sets for your OS and for your audio data. You might consider getting small SSD which would store your OS and the programs - although sound libraries love to install a ton of crap under C:\Program Files so if you're using something like the Native Instruments collection, that would have to go on your music storage drives.

I'll write up some more later, I have to go to a meeting now.

Okay, some follow-ups:

The server board I'm using is a DQ67SW. LGA1155, Q67 chipset. I think it runs around $130 or so.

The major thing that you have to consider is that both Windows and Mac OS X aren't hard real time systems - like QNX. Audio work is time critical - you need to meet a certain latency threshold, and during recording, you need to get that data through your DAW software and onto disk within a reasonable timeframe. Because of this, you want to have the absolute minimum running on these machines. Something that is key is keeping a lot of crap out of the kernel space - this means device drivers and stuff like that. All of my audio machines use pretty simple hardware - Intel GPU's and that kind of thing. I'd strongly recommend keeping fancy video cards out of this box, simply because they have massive device drivers that could cause potential issues. Having dual monitors is a good feature, but I think the new Intel GPU's can do that for you.